Optical networks are capable of carrying the highest bandwidth amongst various forms of currently available network communications technologies and, as such, are well suited for high-speed, high-bandwidth network communications.
Optical regenerators and amplifiers are important building elements of a modern optical network. Regeneration is done because the links or spans between communicating elements (or nodes) in an optical network may be too long for optical signals to travel from one element to another. In this case, the signal can become so degraded that it may not be reliably decoded. Optical regenerators help prevent information loss by boosting the degraded signal. Similarly, optical amplification is done to raise optical power levels in long sections of optical fibers in an optical network in order to prevent information loss. Optical amplifiers boost the power of optical signals to higher levels and thereby reduce the noise level.
Optical Signal-to-Noise Ratio (OSNR) is a common metric used to determine whether a signal can be decoded reliably. The lower the level of OSNR, the less likely it is that a signal can be decoded correctly. Regenerators and amplifiers help improve (increase) OSNR, thereby improving the reliability of communications.
Raman amplifiers are a type of optical amplifiers that operate based on the Stimulated Raman Scattering (SRS) phenomenon. Raman amplification is stimulated when a lower frequency signal photon induces inelastic scattering of a higher frequency photon in an optical medium. As a result of this stimulation another photon is produced and the added energy of this additional photon is passed into the optical medium, thereby resulting in optical amplification.
Regenerators and amplifiers, including Raman amplifiers, are expensive devices. They require equipment to be installed, serviced, and maintained at each physical regeneration and amplification location. Such locations can be geographically distant from one another, difficult to access, and often necessitate paying for a lease to use the site. Therefore, it is in the network provider's interest to minimize the use of optical regeneration and amplification.